An ink jet printer is as an example of a printing apparatus that ejects droplets of ink onto a recording medium such as a sheet of paper for printing a specific job. Ink jet printers include one or more print engines having at least one ink jet print head provided with an ink cartridge that accommodates the ink. In operation of the print engine, ink is supplied from the ink cartridge to ejection nozzles in each print head so that a printing operation is performed by ejection of the ink droplets from selected ejection nozzles.
Present high speed ink jet printers include wide array print heads capable of printing on wider (e.g., >20 inch) mediums at high resolutions. One major issue with such ink jet print heads is the clogging of nozzles due to evaporation of solvent from ink, resulting in an increase in viscosity, an accumulation of paper dust at the nozzle surface, and an intrusion of air bubbles. Each of these results causes a failure of regular nozzle functionality and degraded print quality.
A Print Verification System (PVS) is typically used to immediately capture the printed output exiting the printer and provide feedback on any nozzle dysfunction to a controller. Most current PVSs provide an approximate estimate of the location of defective nozzles, but do not provide any information regarding the type of defect.
Accordingly, a PVS system that automatically detects, locates, classifies the type of defect and counts the number of defective nozzles is desired for facilitating efficient corrective/cleaning processes.